No, it is listed in the release notes that blurred layers is not supported on the iPhone 4. It is *not* listed as a "known issue" and so will not be "fixed".
It might come in future releases, on betas 1 and 2 the lock screen on iPhone 4 was just a black screen and they added the blurred effect on beta 3.
Then it would be listed under known issues if listed at all. Apple wouldn't list it as unsupported. Remember these releases are for developers. They have to know what is supported in each device.
What's supported and what's not supported isn't fixed. Further optimizations could make Apple reevaluate their decision to exclude the 4.
I'm sure it would be nice for owners but I don't see Apple devoting much to a phone that old. Features also have to be tested. I doubt there will be many more beta releases at this point.
There will be at least 3 more betas before the GM version (based on previous years),
The iPhone 4 isn't that old, as a matter of fact the iPhone 3GS had versions 3.0, 4.0, 5.0 and 6.0.